ADDITIONAL MINOR ABNORMALITIES 61 



ADDITIONAL ABNORMALITIES. 



Having reference for the most part to single organs. 



Barbels. Additional barbels in Ameiurus natalis (Eigenmann and Cox 62}. Doubling of a 

 regenerated barbel in Silurus (Eoth 209). 



Brain. Anomalous cerebellum of Alopias (Leger 138). 



Torpedo embryo with a neuro-epithelial organ in relation with the cerebral ganglia 

 (Coggi 40). 



Eyes. 



Absence of one eye. Giraldus Cambrensis (III. c. x.) speaks of eels, trout and perch existing in the 

 lakes of Snowdon which only possessed the right eye but were invariably blind with the 

 left (quoted from Day 54 H. P- 102). It is stated somewhere that fish with only one 

 eye are still from time to time caught in the district named. 



Lowne (146 525-6, pp. 124-5) catalogues the head of a large carp with entire 

 deficiency of the eye on the left side, and the head of a barbel with absence of the right 

 eye. 



Williamson (270 p. 53) describes an angler-fish with only one eye. 

 See also Stoddart (239) quoted in footnote on p. 46 of this work. 



Atrophy. Mencl (157) records the presence of two lenses without other eye structures. Compare 

 the case of parasitism described on page 60. A somewhat similar condition in which the 

 lens alone of all the eye structures has survived is shown in PI. XXVI, fig. 112, of this 

 work, which illustrates a transverse section of a single atrophic head. The mouth, the 

 lower jaw, the trabeculae, and the palato- quadrates are absent. One large lens, clothed 

 with muscle-fibres, is present on the right side ventrally and compresses the lower part 

 of the brain. A second smaller hour-glass-shaped lens lies beside it, all other ocular 

 structures being deficient. 



Egg, double. Vayssiere (264) describes an egg capsule of the porbeagle shark, which contained two 

 separate ova, each with a growing blastoderm. A somewhat similar instance in Scyllium 

 is recorded by Joseph (120). 



Fins, absent or defective. The following instances, collated by Freund (70), fall to be added to 

 the list on p. 55 : a Plwxinus laevis with defective pelvic bones (Fatio), and another with 

 an absent pectoral (Lunel) ; Silurus glanis -with atrophic pectoral fin (Jaquet); Leudscus 

 dobula without pelvic fins (Martens) ; Sqtuilius cavedanus without pelvic fins and with 

 reduced pelvic girdle, carps without pelvic fins but with pelvic girdle and musculature 

 (Hofer) ; goldfish without dorsal fins (Hofer) ; goldfish without left pelvic fin (Day) ; 

 thirteen examples of Gasterosteus pungitius without pelvic fins or girdles (Day) ; goldfish 

 with various other abnormalities of fins, including triple or even quadruple lobing of the 

 caudal fin (Pavesi, Watase, Cori, Kishinouye). See Freund, loc. cit. p. 726-7. For other 

 papers on goldfish, or references to goldfish literature, see Bateson (19 pp. 309, 451, 453), 

 Pouchet '(194), Eyder (210), Stoll (240), Storch (240a), Tornier (249). 



Fin rays. Unusual elongation of second anal fin ray in Protcracanthus (Pellegrin 186). Various 

 minor abnormalities in Cyprinidae (Knauthe 125). See also p. 55. 



Gill absent in trout (Stoddart 239) quoted in footnote on p. 46. 



Gill-cleft. Reduction of the last gill-cleft in Squalus acanthias L. (Ekman 63b). 



Gill-tufts present instead of teeth (see under Teeth). 



Gill-covers. Day (54 II. 102) mentions trout from Maltham Tarn, Yorkshire, with imperfectly 

 developed gill-covers, and Lowne (146 p. 55) catalogues a similar specimen from Loch 

 Assynt, Sutherlandshire. See also Miall (158a). Some further instances are given by 

 Hofer (96a). 



